This invention relates to molded fastener members useful for engaging loops and the like.
In hook and loop fasteners, typically an extensive field of molded hooks aligned in adjacent rows on one half of the fastener, the "hook element", engages mating loops or anchored fibers on the other half of the fastener, the "loop element."
Fastener members of a molded hook element typically are integrally formed with the base, each including a stem extending from the base to a head with a crook which overhangs the base. Often the mold cavities in which the hooks are formed have no moving parts, the hook fastener elements being pulled from the mold cavities by resiliently distorting the solidified crook portions of the hooks. For molding a running strip of such a hook element, a rotating mold roll is employed. For discrete items, cyclable injection molding techniques are employed. Typically in either case, the mold is formed of a stacked series of plates, with the overhanging crooks of the hooks confined to face in the direction of the planes of the mold plates.
One characteristic of fastener components is the shear strength of engagement between them. This refers to their ability to resist disengagement when subjected to a force acting along the plane defined between the mating faces of the hook and loop elements. The shear strength often determines the strength limit of the attachment. In many applications, the fastener is applied with the hook elements aligned to face in a first direction, but the shear load applied to the fastener component is in a direction that is perpendicular to, or at a substantial angle to, the direction in which the hooks face. For example, hook fastener components in some disposable diapers face in a direction generally parallel to a baby's waistline, yet the forces on the fastener caused by motion of the baby's legs are substantially perpendicular to the waistline.